1. Field of the Invention
The present invention relates to a communication apparatus capable of communicating with an external apparatus, a control method, and a computer-readable storage medium.
2. Description of the Related Art
There is a communication system operable in conformity with High Definition Multimedia Interface (HDMI) (registered trademark) standard, which is hereinafter referred to as an “HDMI system.” The HDMI system includes a source apparatus and a sink apparatus. The source apparatus is configured to transmit video data. The sink apparatus displays video data received from the source apparatus on its display device.
Further, in the HDMI system, the sink apparatus is operable based on a CEC command (i.e., a command that conforms to Consumer Electronics Control (CEC) standard) to control source apparatus.
The sink apparatus has a plurality of HDMI terminals and can receive video data from a plurality of source apparatuses connected to respective HDMI terminals.
If the above-described sink apparatus detects any source apparatus being in an “active state” (i.e., a state where the source apparatus can transmit video data to the sink apparatus) among a plurality of source apparatuses connected to respective HDMI terminals, the sink apparatus selects an HDMI terminal to which the detected active source apparatus is connected. Further, the sink apparatus causes the display device to display video data received from the source apparatus corresponding to the selected HDMI terminal and designates the source apparatus corresponding to the selected HDMI terminal as an operational target to be controlled based on a CEC command.
For example, to confirm a source apparatus being currently in the active state, a sink apparatus discussed in Japanese Patent Application Laid-Open No. 2009-229924 is operable to transmit a <Request Active Source> command, which is one of CEC commands, to all source apparatuses connected to respective HDMI terminals.
When the active source apparatus has received the <Request Active Source> command transmitted from the sink apparatus, the active source apparatus generates an <Active Source> command including a physical address of the source apparatus itself. Further, the active source apparatus transmits video data to the sink apparatus and transmits the generated <Active Source> command to the sink apparatus and all of other source apparatuses.
When the sink apparatus has received the <Active Source> command from the source apparatus, the sink apparatus confirms the presence of the source apparatus being currently in the active state. Further, the sink apparatus selects an HDMI terminal corresponding to the source apparatus being currently in the active state among a plurality of HDMI terminals in accordance with the physical address of the source apparatus included in the <Active Source> command received from the source apparatus.
However, the source apparatus having received the <Request Active Source> command from the sink apparatus is not configured to determine whether the physical address of the source apparatus is correct information usable when the sink apparatus recognizes the HDMI terminal corresponding to the source apparatus. In such a case, the source apparatus having received the <Request Active Source> command from the sink apparatus may erroneously transmit an <Active Source> command including an incorrect physical address of the source apparatus to the sink apparatus.
The sink apparatus having received the <Active Source> command from the source apparatus is conventionally configured to simply select an HDMI terminal according to the physical address of the source apparatus, irrespective of correctness of the physical address of the source apparatus included in the <Active Source> command.
Therefore, if the <Active Source> command having been received from the source apparatus includes an incorrect physical address of the source apparatus, the sink apparatus selects an HDMI terminal different from the HDMI terminal corresponding to the source apparatus being currently in the active state.
Thus, even when a source apparatus being currently in an active state is correctly detected from a plurality of source apparatus, the sink apparatus does not select the detected active source apparatus as an operational target to be controlled based on a CEC command.